The police in Hamilton say a violent attack that left a young man with serious facial injuries was planned and unprovoked.
They say a group of nine seventh-form students were attacked by a group of three men and a woman as they walked along Naylor St at 2am on Tuesday.
Detective Constable Andrew Hawke says one of the students needed surgery to his jaw after being knocked unconscious and kicked in the face and head.
He says those attacked have no idea why they were targeted.
The students were robbed of their cellphones and other items.